tingling shocks when using water

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  #1  
Old 03-29-06, 12:56 PM
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Unhappy tingling shocks when using water

When sitting in a water filled tub, and touching the metal faucet handle, I get these tingling shocks.
When standing outside on a wet concrete patio in my bare feet, and turning on the faucet with wet hands I get similar tingling shocks.
Everything else seems to be OK.

Where do I start trouble shooting this??

Country Boy
 
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  #2  
Old 03-29-06, 01:03 PM
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Obviously everything is NOT okay.

Start by checking for proper grounding of the electrical panel to the water pipes and by checking for illegal ground connections (ie other connections to the water pipes).
 
  #3  
Old 03-29-06, 03:05 PM
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The problem is that testing to see if the problem is resolved, could be deadly in the right circumstance. Please take this problem very seriously.

If you have a voltage meter or simple voltage tester, does it register anything between the water faucet and a known good ground (ground prong of a grounded receptacle)? If so, turn off 1 circuit breaker in the panel at a time until the tester registers nothing. The last one turned off is the offending circuit and should be left off until fixed. If you have an electric water heater, start with it's breaker. Once we find the offending circuit, we can figure out how to go from there.

If you can't find a way to test this without feeling for a "tingle", please call an electrician immediately and don't use either faucet until the problem is resolved.

Doug M.
 
  #4  
Old 03-29-06, 03:20 PM
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This can be a tough problem to troubleshoot, since it is possible, even likely, that the electrical bonding to the water system can be intact. Suppose the water heater is leaking current into both the water supply pipes and the
EGC/bonding system. You should not get much voltage reading between the water pipe and the electrical ground. What you may see is a significant voltage between the DRAIN piping and the supply piping. I don't think drain piping is typically connected to the supply pipes, thereby creating the possibility of a difference in potential.
 
  #5  
Old 03-29-06, 03:48 PM
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I would definately not let this ride for very long. That kind of free current running around could cause small arcs somewhere and possibly a fire.
 
  #6  
Old 03-29-06, 05:36 PM
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Originally Posted by telecom guy
it is possible, even likely, that the electrical bonding to the water system can be intact.
I look forward to the explanation for this is possible given the symptoms.


> Suppose the water heater is leaking current into both
> the water supply pipes and the EGC/bonding system.
> You should not get much voltage reading between the
> water pipe and the electrical ground.

Whoa. If it is bonded, you should get about 0V.


> What you may see is a significant voltage between the DRAIN piping
> and the supply piping.

If it is bonded, you should get about 0V.


> I don't think drain piping is typically connected to the supply pipes,
> thereby creating the possibility of a difference in potential.

which is why it must be bonded.


Something is not bonded.

The obvious solution is to bond everything correctly.

At that point, a breaker might trip. Regardless, the tingling problem goes away.

If a breaker doesn't trip, it is still wise to check for the source of the voltage.
 
  #7  
Old 03-29-06, 07:29 PM
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The obvious solution is to bond everything correctly.
Obvious to who? Nobody bonds the drain system in a house, do they? Of course in modern construction, the material of drains is plastic.

Also, the patio shocks are "clearly" caused by a supply pipe system that is being driven by current to cause it to be above local ground potential. Bonding won't solve the barefoot shock issue on the patio.

The solution is to find the culprit device and fix it. It could be your own or your neighbors water heater, well pump, or something else connected to the supply water system.
 
  #8  
Old 03-29-06, 08:16 PM
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Could also be a utility problem
open or high resistance primary neutral
This is the kind of stuff that makes cows stop giving milk
Is there a ground wire run to your water meter and jumpered around it?
The old practice of picking up a cold water pipe anywhere is no longer practiced because of the impact of intermediate remodeling [which can disrupt the ground path]
Do you have metal cold water feed?
Is there a ground rod [probably not]
Alternative test ... turn off your main and see if you can get a reading ANYWHERE at all - and try one of the little EMF sensitive testers like the one Greeenlee makes [GT-11]
If you have a well, is there a bonding connection to the metal well collar?

Having any odd electrical effects otherwise?
I have seen BX cables welded to air conditioning ducts by an internal fault that didn't trip the breaker.

I encourage you to get a GOOD electrician in if you can't solve this presently.
Electricity kills.
 
  #9  
Old 03-29-06, 09:47 PM
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interior metal piping

Originally Posted by telecom guy
Obvious to whom?
Everyone following the NEC.

> Nobody bonds the drain system in a house, do they?

I do. You should.

The whole point of bonding is too avoid this type of problem.

> the patio shocks are "clearly" caused by a supply pipe system
> that is being driven by current to cause it to be above local
> ground potential.
> Bonding won't solve the barefoot shock issue on the patio.

You are probably mistaken. It will take a while for you to realize why.


> The solution is to find the culprit device and fix it.

Bonding is the first step as that might cause an OCPD to open.

> It could be your own or your neighbor's water heater,
> well pump, or something else connected to the supply water system.

Could be.

But proper bonding will drive down the voltage no matter what the source.
It should eliminate the voltage in the bathtub (for all practical purposes).
 
  #10  
Old 03-29-06, 10:10 PM
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Originally Posted by RobertWilber
Could also be a utility problem - open or high resistance neutral
Yes.

> Is there a ground rod [probably not].

Wouldn't help either problem.

> turn off your main and see if you can get a reading ANYWHERE at all

Could pinpoint the branch circuit even.


> I have seen BX cables welded to air conditioning ducts
> by an internal fault that didn't trip the breaker.

That's why I wouldn't give up the hunt for the problem after bonding.

> I encourage you to get a GOOD electrician in if you can't solve
> this presently. Electricity kills.

This problem won't just go away forever by itself.
 
  #11  
Old 03-30-06, 12:40 AM
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Call your power company now. They are open 24/7 for problems of this nature, this could be a poor service neutral, they will check it for free.

If you have any neighbors on the same transformer it might be one of their service neutral connections.
 
  #12  
Old 03-30-06, 05:12 AM
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bolide:

I agree with you that the tingling between the tub and the faucet indicates a bonding problem at the tub. It is very likely that the drain pipes are not bonded. NEC requires this bonding, but I've never actually seen this done, probably because people assume that the drain stack is 'grounded'.

I disagree with you on the barefoot shock issue at the outside tap, but only because you can have this particular problem with 'nothing to bond'. In a home with all of the NEC mandated grounding electrodes, and with all metal systems (pipes, structural metal, ducts, etc) properly bonded, you can still have potential difference between the earth and the metal piping systems. This is because the metal piping systems will be bonded to earth potential _at the location of the earth electrodes_, but away from the earth electrodes the earth potential may be different. In this scenario, the bonding of the outdoor spigot actually makes the symptoms of the problem worse. (Not that I would advocate removing this bond, however.)

Of course, you could 'bond' the earth near the outdoor spigot, but adding additional grounding electrodes or a ground grid, and then bonding these to the electrical system ground.

To the original poster: There are lots of ways that you can go, but I'd suggest that you answer a few questions here:

Is the piping involved metal or plastic?

Do you have an electric hot water heater?

Is there a 'ground' wire that goes from your electrical panel or meter to your cold water pipe?

Is there a 'jumper' wire that goes around your water meter?

-Jon
 
  #13  
Old 03-30-06, 06:45 AM
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Smile Thanks

Well folks, you've certainly given me much to think about and do.

First of all your encouragement to take this seriously ..... I am! especially with what could be serious implications.

I do have an external ground/ metal bar outside my home (under several feet off dirt).
I have large diameter ABS pipe drainage to my septic system.

I have ABS water supply line from my concrete walled well.

Another clue could be that this is an intermittent problem. The tingling lasts for 2-3 minutes and then for longer periods of time there is no tingling. This is the same for the tub and patio scenario

I also have a gas water heater (with fan).

I'm at work now, but will do the requested testing with an electrician when I get home. I'll keep you posted.... and Thanks for all the advice.

 
  #14  
Old 03-30-06, 06:57 AM
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Given that your water supply and main line to your septic system is plastic:

1) Is any of the internal water or drain piping metal?
2) Do you have a pump inside your house?
3) Is your bathtub metal or plastic?
4) Is your hot water heater gas or electric?

-Jon
 
  #15  
Old 03-30-06, 08:10 AM
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Originally Posted by winnie
I've never actually seen this done
It's easy to do on 2". On 4" you have to improvise.

> probably because people assume that the drain stack is 'grounded'.

More likely that there used to be copper supplies to a stainless sink.
Regardless, grounded and bonded are not the same thing.



> I disagree with you on the barefoot shock issue at the outside tap,
> but only because you can have this particular problem with 'nothing to
> bond'.

You can. But what is the source of the voltage?

> In a home with all of the NEC mandated grounding electrodes,
> and with all metal systems (pipes, structural metal, ducts, etc)
> properly bonded, you can still have potential difference between
> the earth and the metal piping systems.

Shouldn't be that much.


> This is because the metal piping systems will be bonded to earth
> potential _at the location of the earth electrodes_, but away
> from the earth electrodes the earth potential may be different.

How there could be a higher potential in the ground than in the piping requires an explanation. Apparently there is a fault.


> In this scenario, the bonding of the outdoor spigot actually makes the
> symptoms of the problem worse. (Not that I would advocate
> removing this bond, however.)

I agree.
But if there is a higher potential in the spigot than the earth, then the neutral is overloaded or something is not properly bonded.


> Of course, you could 'bond' the earth near the outdoor spigot, but adding
> additional grounding electrodes or a ground grid, and then bonding these
> to the electrical system ground.

That could be the only solution depending on the source of the voltage.

What will be interesting is if we reach the day when four-wires come in from the poco and there is no way for neutral current to get into the earth.
 
  #16  
Old 03-30-06, 09:31 AM
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2-3 minutes there is tingling. Is this the time that the well is running? Interesting.
Water is somewhat conductive, so a well motor fault with a defective bonding scheme may pose a hazard, even with plastic pipes.

I fail to read in the NEC any positive requirement to bond the drain pipes. 250.104 (A) talks to metal water piping. I don't consider drain pipe to be water pipe.
250.104 (B) talks to "other" metal piping, including gas pipes. But only if they are "likely to be energized". I suppose a argument can be made there.
 
  #17  
Old 03-30-06, 02:26 PM
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> I suppose a argument can be made there.

Probably the NEC should be stricter about metal bathtubs with metal drains.

The issue is not merely whether the drain pipes are likely to be energized (they probably are not), but whether they are likely to be at the same potential as the water pipes.
Only bonding can assure this.
 
  #18  
Old 03-30-06, 02:52 PM
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To the original poster: be sure to investigate the bonding that bolide is suggesting.

To bolide:

Here is an example of a situation where there was enough potential difference between the grounding electrodes on one side of the house, and the ground near a water spigot on the other side of the house to cause shocks:

http://www.electrical-contractor.net...ML/003127.html

And some other threads at the same BBS covering this issue
http://www.electrical-contractor.net...ML/003117.html

As you suggest, properly bonding the everything will make this much less of an issue. I'd much rather that this current flows through some copper wires than through me. Also note that the root cause of the problem, current flowing through the earth because the power company uses a 'multi-grounded neutral' is not necessarily a _fault_; look up 'single wire earth return' for a method of power distribution that _intentionally_ uses the earth as a conductor. Any separated grounding electrodes will have a potential difference in the presence of such a system.

It is interesting that the NEC requires extreme measures to provide bonding and an equipotential grid around a swimming pool, but doesn't explicitly mention this as a requirement for bathtubs.

-Jon
 
  #19  
Old 03-30-06, 03:07 PM
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I'd agree with telecom's read on this.

If the problem is a malfunctioning piece of utilization equipment, then a lack of bonding at the equipment appears to be the problem.

If the problem is an open neutral, then bonding is just broadening the playing field. Sitting in a bathtub with your toe in the drain, and your other toe on the spigot, with your hand on the floor - aside from being uncomfortable - would result in neutral current flowing out of the bonded drain and water pipes through the person to ground, as the electrons try to get back to their source at the transformer. What changed?

So then should we bond the floor? The tub? How far do we go? How often is it a problem? Is a bonding conductor that less likely to fail than a neutral?

Inside the house, we can actively bond, and thus control fault currents through the use of EGC's.

If it's an open neutral problem, our methods inside the house are actually making things worse, not better. We're putting half the circuit in the hands of the user.

Food for thought.
 
  #20  
Old 03-30-06, 06:50 PM
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You think four-wire is great? How about one-wire?

> the root cause of the problem, current flowing through the
> earth because the power company uses a 'multi-grounded
> neutral' is not necessarily a _fault_;

I didn't call it a fault, did I?
I just think it's another idea whose era will go the way of three-wire ranges and dryers, which although generally safe, certainly are not ideal.

Because the earth is high resistance, it is not usually an issue.
But as Don pointed out, underground metal pipes always become parallel conductors between houses. Nasty.

Four-wire service drops would basically preclude this.
Unfortunately, there are numerous issues that would have to be resolved to ensure safety and how the system handles a lost neutral or detect an open ground.


> look up 'single wire earth return' for a method of power
> distribution that _intentionally_ uses the earth as a
> conductor.
http://en.wikipedia.org/wiki/Single_wire_earth_return

Obviously this leaves a lot to be desired.
It works because it is 12,700V. You can't expect that to work with 120V. Was that your point?


> Any separated grounding electrodes will have a potential
> difference in the presence of such a system.

Therefore, they must be bonded.
If you use #4 copper, the difference should be less than 1V even at 75'.

If there is a circuit dumping lots of current into the earth, then there is little that you can do to escape from it short of covering it with a sheet of very conductive material or a sheet of non-conductive material.


> It is interesting that the NEC requires extreme measures to
> provide bonding and an equipotential grid around a swimming
> pool, but doesn't explicitly mention this as a requirement for
> bathtubs.

It's a small oversight. I guess injury is pretty rare.


If lightning strikes the cast iron or copper vent pipe on your roof and your drains aren't bonded, the lightning will find its on way to your electrical system.
If you are touching the faucet at the time, you'll be one one those paths --- doesn't happen very often.
 

Last edited by bolide; 03-30-06 at 07:08 PM.
  #21  
Old 03-30-06, 07:05 PM
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Originally Posted by Rocky Mountain
If the problem is an open neutral, then bonding is just broadening the playing field.
We call it equalizing the potential.

We don't exactly care what that potential is, just so it's the same everywhere.

> Sitting in a bathtub with your toe in the drain,
> and your other toe on the spigot, with your
> hand on the floor - aside from being uncomfortable -
> would result in neutral current flowing out of the
> bonded drain and water pipes through the person
> to ground, as the electrons try to get back to their
> source at the transformer.

Don't know what to say except that you are mistaken.

Electricity won't run from the bathtub to the floor and back to the bathtub. It doesn't go in circles like that.


> So then should we bond the floor?

The floor is "bonded" to the tub by virtue of the tub sitting on the floor.


> The tub?

The tub is bonded by the drain.


> Is a bonding conductor that less likely to fail than a neutral?

In the grand scheme, who cares?

Both are subject to damage and deterioration. Both need to be maintained.

That's pretty much like asking whether your car's brakes are less likely to fail than your brakelights are to burn out.


> Inside the house, we can actively bond, and thus
> control fault currents through the use of EGCs.

That is not the sole purpose of bonding.


> If it's an open neutral problem, our methods inside the
> house are actually making things worse, not better.

Give a valid example not involving earth contact (e.g., standing outside) that doesn't involve failure to bond something metal.

Like I want to know how the floor got a higher potential than the bathtub that is sitting on that floor.


> We're putting half the circuit in the hands of the user.

What does this mean?
 
  #22  
Old 03-31-06, 10:35 AM
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Think outside the box.

Originally Posted by bolide
We call it equalizing the potential.

We don't exactly care what that potential is, just so it's the same everywhere.
It's hopeless to assume that we can bring everything to the same potential.

Why do 406.3(D)(3)(b) & (c) require isolation of replacement receptacles not connected to an effective fault-current return path? Because if the return path is not there, it's safer to isolate the fault to one receptacle outlet as opposed to trying in vain to raise the potential of the entire system. We'd have to try to raise the potential of the floors, walls ... everything, to the same potential as the fault, and that's impossible.

Sitting in a bathtub with your toe in the drain, and your other toe on the spigot, with your hand on the floor - aside from being uncomfortable - would result in neutral current flowing out of the bonded drain and water pipes through the person to ground, as the electrons try to get back to their source at the transformer.
Don't know what to say except that you are mistaken.

Electricity won't run from the bathtub to the floor and back to the bathtub. It doesn't go in circles like that.
It's not going in circles if the tub is non-metallic. And we can't bond a non-metallic tub. I was not clear enough, I had switched gears, my apologies.

If it's an open neutral problem, our methods inside the house are actually making things worse, not better.
Give a valid example not involving earth contact (e.g., standing outside) that doesn't involve failure to bond something metal.

Like I want to know how the floor got a higher potential than the bathtub that is sitting on that floor.
Backwards. In an open neutral, the bonded metallic items connected to the electrical system assume a higher potential than ground. Therefore, the bonded water pipe becomes a source of neutral current, flowing through the victim, to the floor, seeking the transformer at the street.

Have you never received a shock standing on a wood floor? Carpet? Do you believe that non-metallic surfaces are entirely non-conductive?

We're putting half the circuit in the hands of the user.
What does this mean?
It's an expression coined by a free-thinking electrician who has since passed on. For casual readers, the following is pure theory - always conform to standard practices, always use the EGC, given the fact that everything is bonded and grounded, we must continue to bond and ground everything to ensure the safety of the system. Reader discretion is advised!

There are two methods to controlling and dealing with faults. Double-insulation, and bonding. Bonding is less expensive than double-insulation, thus it's appeal. The problem is, once you start, you can't stop. Any hole in the system compromises safety. Double-insulation is difficult to ensure, given that nothing lasts forever, and appliances subject to use and abuse every day don't last as long as they would in a lab.

As soon as we connect the EGC to an appliance, we are connecting the user (by virtue of the fact that they are touching the metallic case of the appliance) to the system current-carrying neutral. This has to happen, because it is the primary purpose of bonding.
250.4(A)(3) Bonding of Electrical Equipment. Non–current-carrying conductive materials enclosing electrical conductors or equipment, or forming part of such equipment, shall be connected together and to the electrical supply source in a manner that establishes an effective ground-fault current path.
It works, but there is a catch. What is required for a circuit to operate? A complete circuit. Power travels from the transformer, through the ungrounded service conductor, ungrounded feeder conductor, ungrounded branch circuit conductor, load, neutral branch circuit conductor, on back to the XO terminal of the transformer.

When you become in contact with XO of the transformer, you are in contact with half of what you need to receive a shock. Half the circuit is in your hand. This is deemed as acceptable, because if the bonding is intact, and there is an intact path to the transformer neutral, then in the event of a fault a circuit breaker will open due to the sudden increase in current over it's rating. The breaker will trip before someone comes in contact with the fault.

The catch is, if that low-resistance path to the transformer neutral is opened, then anything completing a path back to the source is used, regardless of resistance.

If nothing were grounded, if nothing were bonded, and if every appliance employed a system of double-insulation, it would be a superior system. No user of the system would be in contact with the current-carrying components of the system.

Why is the original poster feeling a tingle? Because he's completing a circuit when he is touching the ground, and an energized pipe. Why does the ground complete a circuit? Because the transformer at the street is grounded.

Think outside the box.
 
  #23  
Old 03-31-06, 03:01 PM
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> It's hopeless to assume that we can bring everything
> to the same potential.

Close enough not to hurt anyone.

> Why do 406.3(D)(3)(b) & (c) require isolation of replacement
> receptacles not connected to an effective fault-current
> return path? Because if the return path is not there,
> it's safer to isolate the fault to one receptacle outlet as
> opposed to trying in vain to raise the potential of the entire
> system.

This is entirely irrelevant. You are comparing apples to automobiles.


> We'd have to try to raise the potential of the floors, walls ...
> everything, to the same potential as the fault,
> and that's impossible.

That's completely untrue.
If the building is sitting on a Ufer ground it impossible for a path to ground to exist anywhere else in the building above that is of any consequence.

If you think otherwise, you need to give an explanation as to how that could be possible.


> It's not going in circles if the tub is non-metallic.

You failed to explain how the floor became energized.


> In an open neutral, the bonded metallic items connected
> to the electrical system assume a higher potential than
> ground. Therefore, the bonded water pipe becomes a
> source of neutral current, flowing through the victim,
> to the floor, seeking the transformer at the street.

I don't know what to say besides this is ridiculous.


> Have you never received a shock standing on a wood floor?
Not really. If it happens, its from contacting a grounded object, not via the floor.

> Carpet?
I can stand on carpet and hold any one ungrounded 120V conductor.


> Do you believe that non-metallic surfaces are entirely non-conductive?

No. But those those not in contact with the earth are not very conductive. Carpet, vinyl, wood, and drywall are lousy conductors.
Tile grout and concrete are conductive especially when wet.

Fiberglass (including shingles) is mostly non-conductive to the extent it is clean and dry.

> As soon as we connect the EGC to an appliance,
> we are connecting the user (by virtue of the fact
> that they are touching the metallic case of the appliance)
> to the system current-carrying neutral. This has to happen,
> because it is the primary purpose of bonding.
>
> It works, but there is a catch. What is required for a circuit
> to operate? A complete circuit.

Not just that.

Electricity run downhill so to speak.
If you live above a dam and the dam breaks, you won't be harmed.

> Power travels from the transformer, through the ungrounded
> service conductor, ...
> back to the XO terminal of the transformer.
>
> When you become in contact with XO of the transformer,
> you are in contact with half of what you need to receive a
> shock.

If you go down to the lake and put your toe in it, and the dam breaks, absolutely nothing happens to you.

> The catch is, if that low-resistance path to the transformer
> neutral is opened, then anything completing a path back
> to the source is used, regardless of resistance.

But in inverse proportion to the resistance.

And you must get in the way of electricity headed downhill.

It won't run up through the walls to get upstairs.


> Why is the original poster feeling a tingle? Because he's
> completing a circuit when he is touching the ground, and
> an energized pipe. Why does the ground complete a circuit?
> Because the transformer at the street is grounded.

And because the water pipe isn't.

If the water pipe were bonded, the voltage would be below the threshhold that a human can feel.
 
  #24  
Old 03-31-06, 06:45 PM
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Originally Posted by bolide
We'd have to try to raise the potential of the floors, walls ... everything, to the same potential as the fault, and that's impossible.
That's completely untrue.
If the building is sitting on a Ufer ground it impossible for a path to ground to exist anywhere else in the building above that is of any consequence.

If you think otherwise, you need to give an explanation as to how that could be possible.
If you energize that Ufer, or any electrode, you will not raise the voltage of the material and soil surrounding that Ufer for any considerable distance.

Drive a ground rod and energize it. What is the voltage of the soil 6" from it? It'll bet you a steak dinner it's nowhere near 120V. The same holds true for a Ufer. If you think that the Ufer some sort of fortress of defense, maintaining a set potential level for the entire structure, you're mistaken.

I'll put it this way: Do you think the potential of the tile in a kitchen is guaranteed to be at the same potential as the ufer, embedded in concrete, in the footer below the basement?

It's not going in circles if the tub is non-metallic.
You failed to explain how the floor became energized.
The floor was not energized. The pipes bonded to the system neutral became energized from an open neutral. The floor was not bonded to the system, so it was at a different potential.

In an open neutral, the bonded metallic items connected to the electrical system assume a higher potential than ground. Therefore, the bonded water pipe becomes a source of neutral current, flowing through the victim, to the floor, seeking the transformer at the street.
I don't know what to say besides this is ridiculous.
I mean no disrespect by this, it's an honest question: Do you need me to draw you a picture? If the service neutral opens, all EGCs and appliances connected to the EGCs, all grounding electrodes, all that normally non-current-carrying metal is now energized, looking for a neutral path back to the source. Imagine normal neutral current flow, and then imagine what it would do if the service neutral were severed.

Electricity runs downhill so to speak.
If you live above a dam and the dam breaks, you won't be harmed.
You are operating under a misconception. Electricity seeks any path back to it's source. It does not get back to the service, see a roadblock, and say, "Well, nuts, it's against the NEC for me to head up the grounding conductors and find another way around." There is nothing stopping it.

The catch is, if that low-resistance path to the transformer neutral is opened, then anything completing a path back to the source is used, regardless of resistance.
But in inverse proportion to the resistance.
It's looking you right in the eye when you say that.
If a barefoot person touches the service, then they become a parallel conductor with the neutral conductor. Agreed? Now my math sucks, but if you follow my reasoning, I think you'll see where I'm going with this.

Say the service neutral is 0.02 ohms from the service to the transformer.

Say the person's skin resistance at their hand is 5000 ohms, and their contact with the ground is 5000 ohms. The resistance of the soil is 500 ohms. The resistance of the ground rod at the transformer is 100 ohms.
5000 + 5000 + 500 + 100 = 10600 ohms.

The resistances are a constant: 10600 ohms or .02 ohms.

.00018% of the available neutral current will travel through the human. 99.99982% of the current will travel through the neutral wire back to the transformer.

Let's say that there's somehow 150 amps of unbalanced current on the service when the person is touching it. They've got the big screen running. 0.00027 amps is flowing through the human being, to the transformer. This is well below human perception. Thus, you say, "there's no current flowing through the person."

But there is: it's just very very very very small.

Now remove the neutral conductor. How much of the current is flowing through the human now?

And because the water pipe isn't (bonded).

If the water pipe were bonded, the voltage would be below the threshhold that a human can feel.
If the water pipe is bonded, and the person is touching it, and the neutral is open, trust me, they'll feel it. It might be a tingle, it might be a real kick in the pants; depending on their skin resistance, and how they stack up against the other parallel paths: the grounding electrodes and who knows what else.
 
  #25  
Old 03-31-06, 10:50 PM
bolide's Avatar
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Originally Posted by Rocky Mountain
If you energize that Ufer, or any electrode, you will not raise the voltage of the material and soil surrounding that Ufer for any considerable distance.
How is this relevant in the least?
You are in the house, not in the soil.

> If you think that the Ufer some sort of fortress of defense,
> maintaining a set potential level for the entire structure,
> you're mistaken.

You are mistaken. The Ufer rings the entire building. There is no path to ground that doesn't pass through the Ufer.
Therefore, there can be no lower potential anywhere within the structure.

You can cut the service neutral, bolt the 2/0 ungrounded service conductor to the GEC/Ufer in its place, and I can stand there and work on the panel barehanded (at least until it heats up).

Voltage is not absolute. It's a difference. No difference, no voltage, no current flow.


> Do you think the potential of the tile in a kitchen is
> guaranteed to be at the same potential as the ufer,
> embedded in concrete, in the footer below the basement?

No. What I guarantee (assuming rebar bonded throughout) is that the potential cannot be lower.

> The floor was not energized.
Then you can't get electricity from the floor through your body into the metal piping.


> The pipes bonded to the system neutral became energized
> from an open neutral.
> The floor was not bonded to the system, so it was at a
> different potential.

You failed to explain how this is possible.
I mean no disrespect by this, but you are mealy-mouthing words here.

Either the floor is at a lower potential, or it is not.
If you say it is at alower potential, then explain the path that it takes to X0 that has less resistance than the grounded metal piping of the house.


> I mean no disrespect by this, it's an honest question:
> Do you need for me to draw a picture?

Yes.


> If the service neutral opens, all EGCs and appliances
> connected to the EGCs, all grounding electrodes,
> all that normally non-current-carrying metal is now
> energized, looking for a neutral path back to the source.

This is always the case.

The difference is that the metal neutral normally provide a low-resistance path that makes all other paths de minimis.


> Imagine normal neutral current flow, and then imagine
> what it would do if the service neutral were severed.

What about it?

I don't have to imagine. I've seen it quite a few times.


> You are operating under a misconception.

Point your finger at yourself.


> Electricity seeks any path back to it's source.
> It does not get back to the service, see a roadblock,
> and say, "Well, nuts, it's against the NEC for me to
> head up the grounding conductors and find another
> way around." There is nothing stopping it.

That's a straw man.
Please try to stick to the facts, not imagination.


> If a barefoot person touches the service,
> then they become a parallel conductor with the neutral
> conductor. Agreed? Now my math sucks, but if you follow
> my reasoning, I think you'll see where I'm going with this.

I mean no disrespect by this, but your reasoning is not as good as your math.


> Say the service neutral is 0.02 ohms from the service to the
> transformer.
> Say the person's skin resistance at their hand is 5000 ohms,
> and their contact with the ground is 5000 ohms.
>The resistances are a constant: 10600 ohms or .02 ohms.
> .00018% of the available neutral current will travel through
> the human. 99.99982% of the current will travel through the
> neutral wire back to the transformer.

Fair enough.

> Let's say that there's somehow 150 amps of unbalanced
> current on the service when the person is touching it.
> They've got the big screen running. 0.00027
> amps is flowing through the human being, to the transformer.
> This is well below human perception.
> Thus, you say, "there's no current flowing through the person."

Correct, de minimis.

> But there is: it's just very very very very small.

Correct.


> Now remove the neutral conductor.
> How much of the current is flowing through the human now?

That is a straw man argument: you have the person in contact with the earth.

I specifically set forth that the person has to be in the interior of the house, namely, in the bath tub.



> If the water pipe is bonded, and the person is touching it,
> and the neutral is open, trust me, they'll feel it.

You need to draw a picture showing the path taken by the current.


> It might be a tingle, it might be a real kick in the pants;
> depending on their skin resistance, and how they stack up
> against the other parallel paths: the grounding electrodes
> and who knows what else.

If everything inside the house is bonded correctly, I'll sit in a tub of salt water on the second floor with my foot on the drain and with one hand on the faucet and the other on the tile floor while you cut the neutral at the service head.

Fair enough?
 

Last edited by bolide; 03-31-06 at 11:02 PM.
  #26  
Old 04-01-06, 01:50 AM
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Do I have this strait?


Bonding essentially puts everything bonded at the same potential, as a single conductor. Typically everything that is bonded is bonded to the EGC and to the grounded service neutral in the main service disconnect, and is at the same potential.

With an open service neutral voltage will be present on any conductor bonded to the neutral in the main. Since the purpose of bonding is to have an equal potential, everything that is bonded will now have the same voltage present on it. The voltage present would be dependent on the resistance of the loads on each leg and of the ground. In the event of a ground fault it would be 120 volts.

If outside, since no two points of earth are at the same potential, contact with a bonded conductor with a voltage present would put your body in series with the current flow. If inside, on a well insulated surface, you would have to come into contact with bonded conductors at two points and your body would be in parallel with the current flow.

I still think a call, without delay, to the POCO should be the first step.
 
  #27  
Old 04-01-06, 02:31 AM
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> Bonding essentially puts everything bonded at the same potential, as a single conductor.

Correct.
When we say a metal pathway, the idea is that it is such a good conductor that it has a much lower potential than any non-metallic pathway.

Hence, the current on other pathways is negligible (present, but of no real consequence).

> Typically everything that is bonded is bonded to the EGC and
> to the grounded service neutral in the main service disconnect,
> and is at the same potential.

Correct.


> With an open service neutral, voltage will be present on any
> conductor bonded to the neutral in the main.

Again, this is true (wrt earth) regardless of whether the neutral is open.
The difference is that said voltage changes with respect to earth if the neutral is open.


> Since the purpose of bonding is to have an equal potential,
> everything that is bonded will now have the same voltage
> present on it.

Again, this is true regardless of whether the neutral is open.


> The voltage present is dependent on the resistance of the
> loads on each leg and of the ground.
> In the event of a ground fault it would be 120 volts.

Voltage as measured between where and where?

With or without the neutral connection?


> If outside, since no two points of earth are at the same potential,

There are infinite points at each potential ("shells") and pretty much infinite potentials.


> contact with a bonded conductor with a voltage present
> would put your body in series with the current flow.

Maybe or not. You didn't supply enough information.

As RM pointed out, you are usually in contact with a bonded conductor.


> If inside, on a well-insulated surface, you would have to
> come into contact with bonded conductors at two points
> and your body would be in parallel with the current flow.

This should always be false under all conditions and independent of the surface under your feet.

Or are you referring to grabbing an ECG while it is carrying fault current (or a neutral carrying current) and another ECG that is not carrying current?


> I still think a call, without delay, to the POCO should be the first step.

From the intermittent and cyclic nature of the problem and the lack of any symptom of an open neutral, a fault is indicated in customer's equipment at the premises.

Call an electrician.
 
  #28  
Old 04-01-06, 09:33 AM
Join Date: Mar 2006
Location: Fort Collins, Colorado
Posts: 159
I'm writing from my wife's work, so I'm unable to post a drawing right this second. Forgive the delay, I'll have a passable illustration next post.

Originally Posted by bolide
How is this relevant in the least?
You are in the house, not in the soil.

You are mistaken. The Ufer rings the entire building. There is no path to ground that doesn't pass through the Ufer.
Therefore, there can be no lower potential anywhere within the structure.
The relevance is that all grounding electrodes have a sphere of influence, and can only affect a change within that zone. For example, a benchmark for ground rods is six feet, although it cannot effectively change the voltage of it's surroundings for that entire distance.

The Ufer is an astonishingly effective electrode, hence it's appeal. Given the fact that it's existence is necessary for other purposes makes it even more attractive, since the "electrical" cost to install it is zero, and the cost to attach to it is minimal.

However, it's not all-encompassing. It too has a sphere of influence. In fact, if you look at 250.52(A)(3), a Ufer can be very minimalistic and still qualify as a grounding electrode. How much soil is in contact with the footer, as opposed to being in contact with the entire basement wal and structure above it?

It's not required to create an equipotential bonding grid from the materials at hand. There's no guarantee (or requirement) that the basement wall's rebar be tied to the footer's rebar. So long as you have 20' of rebar (or 20' of #4) then you have satisfied the 250.50 requirement, and the definition in 250.52(A)(3).

So how is it that you believe that the Ufer is so effective it can elevate (or lower) the potential of concrete remote from it? Yes, it will to a distance, but after that point, you have concrete that has it's own porous surface in contact with the soil, that can serve as an alternate path.

My examples of directly energizing an electrode are to illustrate that when you take the matter to an extreme such as that, the shortcomings of the electrode's sphere of influence become more pronounced. It's not magical, it cannot affect material that is beyond it's reach.


The pipes bonded to the system neutral became energized from an open neutral. The floor was not bonded to the system, so it was at a different potential.
You failed to explain how this is possible.
I mean no disrespect by this, but you are mealy-mouthing words here.
I don't know what that means, but I'm sure it isn't good.

One thing is for sure: If I construct a alternate ground fault path, you'll shoot it down. Alternate fault paths are not intentional. For me to describe one would be flying in the face of that. It would look contrived - it would have to, because, let's face it, it would be. How can you predict where electrons will flow in the real world? Are people/animals shocked by unbonded manhole covers a victim of some elaborate scheme, or a lack of attention to detail? Chance and circumstance create the alternate paths.

If you see this as a ploy to escape an explanation, I assure you, it's not. I just can't invent an accident waiting to happen. No matter how slick I could package it, no matter how well it's presented, it would lack the substance of the real thing.

Rather, I am focusing on the limits of the known - the limits of the electrodes, and trying to persuade you that once these limits are known, it's safe to say that in the uncontrolled areas, all bets are off.

Electricity seeks any path back to it's source. It does not get back to the service, see a roadblock, and say, "Well, nuts, it's against the NEC for me to head up the grounding conductors and find another way around." There is nothing stopping it.
That's a straw man.
Please try to stick to the facts, not imagination.
Can you explain this response? That was statement of fact, not flight of fancy.

Now remove the neutral conductor.
How much of the current is flowing through the human now?
That is a straw man argument: you have the person in contact with the earth.

I specifically set forth that the person has to be in the interior of the house, namely, in the bath tub.
Once you admit to the limits of the electrodes, then this transistion in thought will be easy. My belief is, if I can convince you that the electrode has no bearing on the potential of that tile floor, and no deterrent against an alternate path to ground, then the rest will fall into place.
 
  #29  
Old 04-01-06, 09:40 AM
Join Date: Mar 2006
Location: Fort Collins, Colorado
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Sorry, duplicate. Foreign computer!
 
  #30  
Old 04-01-06, 12:24 PM
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> The relevance is that all grounding electrodes have a sphere of influence,

And I refer to a Ufer that covers the footer and ground floor rebar (not to mere electrodes).

> and can only affect a change within that zone.
> For example, a benchmark for ground rods is six feet,

You are off-topic again. I was talking about a Ufer not ground rods.


> The Ufer is an astonishingly effective electrode
> It too has a sphere of influence. In fact,
> if you look at 250.52(A)(3), a Ufer can be very minimalistic
> and still qualify as a grounding electrode.

I am talking about a full Ufer, not just one concrete encased electrode.


> How much soil is in contact with the footer,
100%.

> as opposed to being in contact with the entire basement
> wall and structure above it?
0%.

I already specified that all rebar is bonded.
Rebar-reinforced, poured concrete footer, walls, floor.


> There's no guarantee (or requirement)

I required it to define the hypothetical the problem.

The full Ufer is the ideal case.
If I could convince you that the full Ufer guarantees that the potential of the tile floor can be no lower and therefore cannot be an alternate path to ground, then the rest will fall into place.

Once you see how it works with a full Ufer, we can work backward to less than a full Ufer.


> If I construct a alternate ground fault path,
> you'll shoot it down. Alternate fault paths are not intentional.
> For me to describe one would be flying in the face of that.

Correct.


> It would look contrived - it would have to, because,
> let's face it, it would be.

Correct - like a manhole in your bathroom.
I've never seen a bathroom with a manhole for high voltage electrical systems.


> How can you predict where electrons will flow in the real world?

Science. Electrons don't flow through non-conductive materials as alternate paths to metallic pathways.


> Chance and circumstance create the alternate paths.

Sure. But what will happen to you inside your house?


> If you see this as a ploy to escape an explanation,
> I assure you, it's not. I just can't invent an accident
> waiting to happen. No matter how slick I could package it,
> no matter how well it's presented, it would lack the
> substance of the real thing.

Exactly. Bonding works inside a house.

If it didn't, you could cite real examples.


> Rather, I am focusing on the limits of the known -
> the limits of the electrodes, and trying to persuade you
> that once these limits are known, it's safe to say that in
> the uncontrolled areas, all bets are off.

What uncontrolled areas do you see an a bathroom?

Again, to contain the scope of the discussion, I've tried to stay on the matter of tingling in the bathtub.

You keep leaving the house and going down the street where just about anything is possible.


> Can you explain this response? That was statement of fact,
> not flight of fancy.

Your statement was a strawman argument.
No one was thinking of talking electrons.

So it's a fact generated electricity seeks any path back to its source.

Not one person has failed to acknowledge this.
No one except you stated anything to the contrary.

Congratulations on refuting something that no one believed anyway.


> Once you admit to the limits of the electrodes,

I do.


> then this transistion in thought will be easy.

I hope not!
Your reasoning is unsound and your thoughts stray frequently from the original poster's issue.


> My belief is, if I can convince you that the electrode
> has no bearing on the potential of that tile floor,
> and no deterrent against an alternate path to ground,
> then the rest will fall into place.

You can disconnect the entire outdoor GES (or energize with the other leg from the one energizing the water line). The electrodes make little difference.

Provided that everything inside is bonded, I'm still safe in the bathtub - fiberglass, steel, cast iron.

The GES adds little protection.

With a full UFer (i.e., Ufer's original design for military ammo depots), there can be no alternate paths. That was the primary point of his design.
 
  #31  
Old 04-01-06, 03:54 PM
Join Date: Mar 2006
Location: Fort Collins, Colorado
Posts: 159
You're right. What was I thinking? We always strive to build bunker-quality Ufers complete with telecommunication / substation quality grounding grids for 15' around every house I wire. We have a warranty that states that there is 0% chance of a stray voltage path within spitting distance of any house we wire, or your money back.

In fact, that was in place well prior to those silly gooses at the NFPA kicking the requirements of 250.50 up a notch, last year, to spur the industry into actually using the Concrete Encased Electrode for the first time since Ufer developed the idea, or since it became a recognized electrode, decades ago.

If there is a house on the planet with such a guaranteed equipotential bonding grid installed in the basement, especially one over 2 years old, I would love for you to produce the plans on it. Time for some unrealistic expectations from me.

You are entirely correct: if you seal a house in an airtight box, nothing has a chance of leaking out. I think you're proving my case for me, that existing grounding requirements are not even close to the standard you're raising this to, to maintain your position.

Your mind is closed, and I tire of trying to open it. So I'll politely bow out, and wish you the best.

I hope this brick wall is grounded:
 
  #32  
Old 04-01-06, 05:57 PM
Join Date: Mar 2006
Location: Fort Collins, Colorado
Posts: 159
Wouldn't you know it? After I cooled off, I had an epiphany.

Now, you'll likely disregard this house, as it actually exists in the real world. It doesn't fit into your absurd criteria, which doesn't pain me in the least, because there isn't a house in existence (aside from perhaps an eccentric here and there I am unaware of) that does.

There's a fella named Paul in Greeley, CO, who specializes in a product called cast earth. He has a huge cast earth wall running the length of his house, and cast earth floors. He uses it as his model home to show to clients. He's proud of his floors and walls - he sure isn't going to frame over them with non-conductive wood and all that jazz. No question about some isolated tile surface somehow inexplicably (yet possibly) making a connection with planet earth, I've no need to concoct something. This sucker is earthed, baby - it is earth, with some gypsum and coloring thrown in.

It is a ranch, slab on grade, with a concrete back wall, because it's a earth-friendly bermed house, which saves on material costs of siding and whatnot compared to conventional building. It's an immensely efficient building.

When we were touring his house, I asked how the slab was constructed, and he stated that since cast earth was denser than concrete, he needed no rebar in the slab itself, and chickenwire was used to maintain the surface of the floor. Five will get you ten, he does not have a concrete encased electrode in his slab. Five more will virtually guarantee that he doesn't have one in his footers, either, but just for fun, let's pretend he does.

(Now, of course, we'll overlook the fact that if there was no rebar in his footer, or if it were less than 1/2" rebar, he wouldn't need a CEE at all if he built his house today. The NEC doesn't require us to add a CEE if there isn't one present, but as I said, we'll overlook that. We'll also overlook that this slab wouldn't be recognized as a CEE either, as it's not "concrete".)

Open his neutral, crank up a window air conditioner, a TV, a blender, a skilsaw all on the same phase. Run a bathtub full of saltwater, hop in, stick your toe in the spigot and grab the floor.

Congratulations, I've presented you with a real house that will shock it's occupants with an open neutral without stepping outside. Why we were willing to kill people standing outside, I don't know. They probably had it coming. Please don't act insulted, you've been insulting me steadily through this discussion and I've held my peace.
  • Correct - like a manhole in your bathroom. I've never seen a bathroom with a manhole for high voltage electrical systems.
  • No one was thinking of talking electrons.
  • How is this relevant in the least? You are in the house, not in the soil.
  • Please try to stick to the facts, not imagination.
  • I don't know what to say besides this is ridiculous.
  • You are off-topic again. I was talking about a Ufer not ground rods. (I guess I didn't get the memo that analogies were prohibited in discussion.)
  • If it didn't, you could cite real examples.
  • Your statement was a strawman argument.
  • Congratulations on refuting something that no one believed anyway.

Also, on another note, all the "clarification" you provided that you were discussing a true Ufer, and not the slang "Ufer" used widely in the trade when referring to the CEE, occured all in the same post.
 
  #33  
Old 04-01-06, 08:20 PM
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> We always strive to build bunker-quality Ufers complete
> with telecommunication / substation quality grounding
> grids for 15' around every house I wire.

There you go with knocking down a straw man again.

Your straw man has nothing to do with what I am saying, but that doesn't stop you from setting up your straw man so you can tear it down.

Go right ahead.


> We have a warranty that states that there is 0% chance
> of a stray voltage path within spitting distance of any
> house we wire, or your money back.

That's a complete strawman.
We're talking about within 3' of the bath tub.

You are changing the subject.


> If there is a house on the planet with such a guaranteed
> equipotential bonding grid installed in the basement,
> especially one over 2 years old,

Mine. My house has no earth contact ebcept the basement all of which is poured concrete.
The walls were all poured in one day.
All has rebar wired together for total electrical continuity.

> I think you're proving my case for me, that existing
> grounding requirements are not even close to the
> standard you're raising this to, to maintain your position.

So you concede that the Ufer guarantees that there is no other path to ground. This is progress.

Now we could work from there and look at the situation with lesser bonding... except that your mind is closed.
 
  #34  
Old 04-01-06, 08:27 PM
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> This sucker is earthed, baby - it is earth, with some gypsum and coloring thrown in.

This is no advantage.

> no rebar in the slab itself, and chickenwire was used to maintain the surface of the floor.
> Five will get you ten, he does not have a concrete encased electrode in his slab.

His error.

> (Now, of course, we'll overlook the fact that if there was no rebar in his footer,
> or if it were less than 1/2" rebar, he wouldn't need a CEE at all if he built his
> house today. The NEC doesn't require us to add a CEE if there isn't one present,
> but as I said, we'll overlook that. We'll also overlook that this slab wouldn't
> be recognized as a CEE either, as it's not "concrete".)

Fine.
But you changed the subject.

Grounding electrodes and bonding are entirely different subjects.

We have here failure to bond.



> I've presented you with a real house that will shock it's occupants with an open neutral
> without stepping outside.

I totally agree.
The problem is the failure to bond.
Bond the chicken wire and you equilize the potential.

Furthermore, I specified "not in contact with the earth".
Your "example" clearly is in one where there is contact with the earth and is not on an upper story of wood.

The original poster's bathtub were on the basement floor with an unbonded cast iron drain leading toward the utility pole and his neutral was broken, I would totally agree that this is a problem.

You've been insulting toward me and I've simply addressed your remarks for the silliness that they are.


> * You are off-topic again. I was talking about a Ufer not ground rods.
> (I guess I didn't get the memo that analogies were prohibited in discussion.)

How is an outdoor ground rod an "analogy" for a Ufer?


> * If it didn't, you could cite real examples.

This is an insult? It's a fact.


> * Your statement was a strawman argument.

Look up "straw man argument".


> * Congratulations on refuting something that no one believed anyway.

I didn't believe it, you didn't believe, so for whose benefit did you bring it?
 
  #35  
Old 04-01-06, 08:52 PM
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Originally Posted by RockyMountain
our methods inside the house are actually making things worse, not better.
Wiring your floor with chicken wire and failing to bond it does indeed make things (a little) worse.

My method is to bond it. So that is not "our" method.

Bond the chicken wire and the problem goes away.


> Think outside the box.

To think what? Bonding is dangerous?

It's the best we can do.
The primary problem is failure to bond.
That's the problem that the original poster has.
His plumbing is not bonded.


> Do you need me to draw you a picture?
> I'll have a passable illustration next post.

Ive seen two more posts from you since, but no diagram that puts the floor of a second-story bathroom at lower potential with respect to X0 than that of the metallic piping bonded to the GEC.
We all deserve an epiphany.


> You are operating under a misconception.

What is this misconception?
That electricity will go via the GEC to the copper plumbing, to the bathtub faucet, through a human, down the soil pipe and out into the earth rather than to follow the GEC straight to the properly bonded soil pipe?
Or that the electricity will go through wood rather than through the basement floor and grounding electrodes?

How is this my misconception?
You are the one who appears to believe those things.
I sure don't.


You posited many straw men insultingly suggesting that I believe such nonsense.
I don't believe them.
 
  #36  
Old 04-02-06, 07:52 AM
Join Date: Mar 2006
Location: Fort Collins, Colorado
Posts: 159
Here are my main points:

1. Open neutrals energize the normally non-current-carrying EGC's and everything connected to them. This is an acceptable price to pay for two reasons:
1a. Neutrals don't open that frequently.
1b. So long as a person doesn't complete a path back to the source, they won't get injured.
1c. The EGC system does much more good than harm, there is basically only this one snafu that has a negative consequence.

2. The NEC does not require the kind of bonding you seem to think it does, or should. Examples:
2a. The chickenwire in Paul's slab.
2b. The sewer drain pipe in any dwelling.
2c. The entire rebar structure of a basement.

3. I don't believe we can predict alternate grounding paths at all. I believe that given time, differences in contruction, and chance, that seemingly isolated areas of a house could contain alternate paths.
3a. Fireplaces with no electrical requirements can lead to a gas main which is in contact with the earth. Tile can be in contact with that, and water.
3b. Stone and sometimes brick have a metallic mesh behind them in the facade of a house.
3c. A second floor balcony with a metallic rail can be grounded.

4. I believe that attempting to bond your way out of the open neutral scenario (above and beyond code) is a waste of time and materials.
4a. Because of (1), (2) & (3) above.
4b. If the chickenwire were not present for asthetic reasons, it wouldn't exist, and there'd be no metal to bond at all. You can't fail to bond something with no metal to bond in the first place.

Is bonding a key tool in fixing the original poster's problem? Yes.
Is it a perfect solution, incapable of a backfire of any sort? No.
Is it our best option? Given the hand we're dealt, yes.

Ive seen two more posts from you since, but no diagram...
Don't expect to see one. I explained myself.

>Think outside the box.

To think what? Bonding is dangerous?
No, to think for a moment that there may be one circumstance that bonding may do more harm than good. One small one out of a million good ones. The funny thing is, in reading your posts, I've come to the realization that you do know this, so now I'm thinking you just like to argue, like me.
 
  #37  
Old 04-02-06, 10:45 AM
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> 1. Open neutrals energize the normally non-current-carrying EGCs
> and everything connected to them.
> This is an acceptable price to pay for two reasons:
> 1a. Neutrals don't open that frequently.
> 1b. So long as a person doesn't complete a path back to the
> source, they won't get injured.
> 1c. The EGC system does much more good than harm, there
> is basically only this one snafu that has a negative consequence.

And it is negative pretty much only if the person is outside and barefoot/wet.


> 2. The NEC does not require the kind of bonding you seem to
> think it should. Examples:
> 2a. The chickenwire in Paul's slab.
> 2b. The sewer drain pipe in any dwelling.
> 2c. The entire rebar structure of a basement.

You are mistaken in part.
But whether it is required today is irrelevant.

The danger arises from the failure to bond these things.
Bond them and the danger goes away even when the neutral is broken.

(I also note that failure to bond the entire rebar structure has in real cases led to lightning blowing apart the concrete to reach the other rebar. So proper design for protection from lightning suggests that it ought to be completely bonded.)


> 3. I don't believe we can predict alternate grounding paths at all.

That's pretty sad.

> I believe that given time, differences in construction, and chance,
> that seemingly isolated areas of a house could contain alternate paths.

I don't care what you believe.
Failure to bond is still failure to bond whether you know about it in advance or not, and regardless of whether the NEC required it.
Obviously the trend is toward more bonding and better earthing both of which reduce the risk of electrocution from an open neutral.


> 3a. Fireplaces with no electrical requirements can lead to a
> gas main which is in contact with the earth. Tile can be in
> contact with that, and water.

Failure to bond interior metal piping.


> 3b. Stone and sometimes brick have a metallic mesh behind
> them in the facade of a house.

Failure to bond.


> 3c. A second floor balcony with a metallic rail can be grounded.

Can you reach it from the bathtub?
If so, it is no different than from a pool except that the NEC did not anticipate this.

If it is within 3' of a tub, common sense dictates that it should be bonded.

The NEC is guidelines. It doesn't cover every possible situation that might ever arise.

I doubt that the original poster has a bathtub on his second floor balcony.
So your points are hypothetical situations unrelated to the present issue.

It appears that for the actual issue, we agree that the primary cause is failure to bond interior metal piping and the secondary cause is an electrical fault that needs to be corrected.


> 4b. If the chickenwire were not present ..., it wouldn't exist,
> and there'd be no metal to bond at all.
> You can't fail to bond something with no metal to bond in the
> first place.

That's mostly correct. If you are in earth contact, then it is hard to protect you from shock when the neutral is broken.

For Paul's house with a (hypothetical?) tub on the basement floor, if the chicken wire and the drain were bonded, then do you agree that they have to be at the same potential as the copper plumbing?
 
  #38  
Old 04-02-06, 02:39 PM
Join Date: Mar 2006
Location: Fort Collins, Colorado
Posts: 159
Originally Posted by bolide
2. The NEC does not require the kind of bonding you seem to think it should. Examples:
2a. The chickenwire in Paul's slab.
2b. The sewer drain pipe in any dwelling.
2c. The entire rebar structure of a basement.
You are mistaken in part...

...The danger arises from the failure to bond these things.
Bond them and the danger goes away even when the neutral is broken.
How am I mistaken in part in this comment? Enlighten me.

I believe you know they're not required, as you deleted the portion of my comment that insinuated (halfheartedly) that you truly believed that the bonding you speak of is required.
But whether it is required today is irrelevant.
Not really. The NEC is designed for "the practical safeguarding of persons and property from hazards arising from the use of electricity." What you call "failures" are neither practical, nor significantly increase safety.
I also note that failure to bond the entire rebar structure has in real cases led to lightning blowing apart the concrete to reach the other rebar.
I am interested. Can you produce some examples, or some links?
I don't believe we can predict alternate grounding paths at all.
That's pretty sad.
No, I'm being honest. I don't claim to have a sixth sense in seeing through walls, and I can't optically determine continuity between two points, I have to use a multimeter for that. I'm only human. Truth be known, if I spent any real time walking around looking for alternate grounding paths that aren't hurting anybody anyway, I'd be unemployed. I have work to do.
Obviously the trend is toward more bonding and better earthing both of which reduce the risk of electrocution from an open neutral.
That may well be the case, but in some instances requirements for bonding have lessened from the 2002 NEC to the 2005. See 680.74 of both editions for an example.
3a. Fireplaces ...
Failure to bond interior metal piping.
Let me finish your statement: "...that does not have a circuit likely to energize it." Prey, what size wire would you pull to it?
3b. Stone...facade of a house.
Failure to bond.
Now I've heard everything!
3c. A second floor balcony with a metallic rail...
If it is within 3' of a tub, common sense dictates that it should be bonded.
Why? Is it likely to be energized by something?
It appears that for the actual issue, we agree that the primary cause is failure to bond interior metal piping and the secondary cause is an electrical fault that needs to be corrected.
Close enough to the truth for me not to quibble over details.
For Paul's house with a (hypothetical?) tub on the basement floor, if the chicken wire and the drain were bonded, then do you agree that they have to be at the same potential as the copper plumbing?
No.

The chicken wire might mitigate the voltage difference somewhat, but it doesn't have enough surface contact with it's medium to guarantee any reliable change, which is why we're instructed to build equipotential bonding grids of more substantial material, such as #8 bare, minimum.
 
  #39  
Old 04-02-06, 04:34 PM
bolide's Avatar
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Join Date: Jan 2006
Location: PA
Posts: 1,909
> What you call "failures" are neither practical, nor significantly increase safety.

Bonding does increase safety under the situations that you described.
So if the situation happens with the faucet becoming energized or whatever, the odds of it becoming energized are 100%.
100% chance is more than just "likely". Therefore, bonding is required.


>> I also note that failure to bond the entire rebar structure
>> has in real cases led to lightning blowing apart the concrete
>> to reach the other rebar.
> I am interested. Can you produce some examples, or some links?
Sorry. Try a search.


>>> I don't believe we can predict alternate grounding paths at all.
>> That's pretty sad.
> No, I'm being honest. I don't claim to have a sixth sense

Did you look up straw man yet? No one needs a "sixth sense" for this.

To predict any paths at all merely requires some knowledge and experience of what could make a hazardous situation.

Wet locations and metallic objects are usually fairly obvious.

I'm not saying that I can predict every path, I'm saying that it is pretty sad if you cannot "predict alternate grounding paths at all".


>> Failure to bond interior metal piping.
> Let me finish your statement: "...that does not have a
> circuit likely to energize it." What size wire
> would you pull to it?

Perhaps #12. Tell me what size circuit energized it.
If I think a heavier circuit might energize it, I'll use a heavier ECG.


>>> 3b. Stone...facade of a house.
>> Failure to bond.
> Now I've heard everything!

Lightning protection issues apply here also.
If the metal mesh is bonded, lightning has no reason to penetrate the wall to access the interior wiring and plumbing.


>> For Paul's house with a (hypothetical?) tub on the basement floor,
>> if the chicken wire and the drain were bonded, then do you agree
>> that they have to be at the same potential as the copper plumbing?
> No.
> The chicken wire might mitigate the voltage difference somewhat,
> but it doesn't have enough surface contact with its medium to
> guarantee any reliable change, which is why we're instructed to
> build equipotential bonding grids of more substantial material,
> such as #8 bare, minimum.

Perhaps you could provide a picture of this fence.
What I am thinking of has very substantial surface area, more than a #8 wire every foot.

What it can't do is dissipate a lot of amps.
It will, however, ensure that there is not a lower potential above it.
Hence, voltage to any other bonded object is negligible.
 
  #40  
Old 04-02-06, 09:43 PM
Join Date: Mar 2006
Location: Fort Collins, Colorado
Posts: 159
Originally Posted by bolide
> What you call "failures" are neither practical, nor significantly increase safety.

Bonding does increase safety under the situations that you described.
So if the situation happens with the faucet becoming energized or whatever, the odds of it becoming energized are 100%.
100% chance is more than just "likely". Therefore, bonding is required.
So the solution to the open neutral that's energizing all the bonded piping is more bonding? The bonding connection that is guaranteed to energize the piping is required because the piping is likely to become energized from the bonding connection? Okay, I think I got it.

Are we still cool with hurting people outside, or have we come that far yet?

Are you really thinking that you can outbond an open neutral? Or are you going to concede that an open neutral is the one infrequent event that bonding can't cure?

Let me finish your statement: "...that does not have a circuit likely to energize it." What size wire would you pull to it?
Perhaps #12. Tell me what size circuit energized it.
That's kinda the point, man. There is no circuit to energize it - now, or else I, the code-abiding electrician, would be bonding it.

Give it thirty years, homeowners and chance, who knows? But hooking a #12 to a pipe on the rough isn't going to do much good if a mis-installed 100A feeder I didn't touch forty years after I have forgotten about wiring a house, that has undergone eight remodels in the meantime, is energizing a chunk of pipe that's no longer connected to where I installed my "cautious jumper".

I get the impression (call me paranoid) that you're stating that I am negligent for not bonding everything I see, regardless of the NEC. I am licensed and have a reputation to maintain, and I exercise efficient, safe work practices in line with the NEC. It's difficult enough staying in line with the standards of the code, much less spending two precious hours bonding an isolated I-Beam in a basement, "just in case something happens".

If the metal mesh is bonded, lightning has no reason to penetrate the wall to access the interior wiring and plumbing.
Lightning can and will do as it pleases, despite our efforts to the contrary.

On the slab; I did not install Paul's slab (or wire his house), so I have no idea what size his chicken wire is. I am dubious as to the effect it would have. Figure the surface area of the wire versus the surface area of the earth, the wire would be at a severe disadvantage.

Now, I have to ask you, because this is the core of my astonishment in this discussion: Are you with all honesty telling me you actually take the time to bond isolated metal ducts, gas pipes, sections of water pipe, wire mesh behind stone, all these things that you keep simply replying "Ah ha! That's a failure to bond that!"

Every time you reply this way, it's telling me that if you were to walk into a house and happen across an energized I-Beam from someone else's slipshod work, you would cluck your tongue at the original electrician for not bonding the beam, as opposed to the installer of the conductor that's energizing the beam? As if the original electrician should have seen it coming?

Don't mean to put words in your mouth, but that's how it seems.
 
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